Demi tweeted: "Sad... As if we didn't have enough people glamorizing eat disorders already. Bottom line, it's not "cool" or "artsy" at all. "Would you let someone bring a needle and shoot up on you? Addiction is addiction. (sic)".

Sad... As if we didn't have enough people glamorizing eat disorders already. Bottom line, it's not "cool" or "artsy" at all.

However, the 21-year-old singer was forced to defend herself after her honest comments didn't go down well with her fans. She retaliated: "It's not "shade" and it's not "hate". But someone has to come forward and say it and I'll take the heat for it. (sic)".

Demi then reached out to Lady Gaga directly, writing: "@ladygaga you're SO talented, if not one of the most talented in our industry PERIOD. Dope is INCREDIBLE.. but you don't have to do that (sic)".

Millie, who has worked with Lady Gaga before, performs her stunt by drinking coloured milk before sticking her fingers down her throat and vomiting the liquid back up.

Explaining her floaty Gareth Pugh dress during an interview with Jimmy Kimmel at the South by Southwest festival, she confessed: "That's actually why I wore it because I am really fat right now because I have been eating BBQ.

"I had some at Stubb's because I am playing there and some Salt Lick too. Or any meat that I find on the street, I just eat."